Mechanical grasping is advantageous in a number of applications, including robotics and prosthetics. In industrial and logistics robotics, graspers acquire and move objects as part of manufacturing and packaging processes, such as loading and unloading machines and putting parts into pallets and shipping containers. In typical current practice, gripper fingers are designed for each specific part that is handled, and the programming for performing the grasping and placement process is specialized for the specific task. This customization improves reliability and reduces the possibility of damage to the objects. The creation of specialized hardware and software for each task and item requires skilled labor, increasing costs and decreasing flexibility.
In unstructured environments where household and assistance robotics function, a wide variety of items may need to be reliably and safely grasped and placed. Current grippers are limited in capabilities, with two-fingered parallel-jaw grippers being the most commonly used (e.g., PR2 grippers). These devices are not able to handle a broad range of object sizes and shapes, and ensuring reliability typically requires extensive sensing and control that is expensive and difficult to achieve in unstructured settings.
More elaborate multi-fingered robot hands (e.g., the BarrettHand from Barrett Technology, LLC, of Newton, Mass.) have the mechanical flexibility to grasp a wider range of objects, but they tend to be expensive. To take advantage of the potential of these devices for adapting to diverse items and settings, sensing is used to detect the object properties, and then controllers are utilized for the many degrees of freedom that must be programmed. This approach has proved challenging.
Similarly, current under-actuated hands, which use passive mechanisms and/or compliance to adapt to object geometry, are limited in terms of the range of objects that can be accommodated. Existing under-actuated hands also tend to be expensive to manufacture and many approaches are not robust to the collisions that can occur in unstructured environments, or during programming and system debugging in industrial applications.